No internet on 2gEXT yet there is on 5gEXT

What Firmware version is loaded on the EX? 

>>> latest firmware is installed
What is the Mfr and model# of the main host router the NG extender is connected too?

>>> Sky Hub, model ER115

What is the distance between the main host router and the EX unit? 

>>> about 10 metres. Hub is downstairs, extender one floor up

What channels are you using on the main host router? 

>>> on the page for 2.4GHz it is set to 'auto' in the drop down list. The drop down is a list of integers from 1 to 13. On the 5GHz page it is set to '80MHz ch.36'. The drop down has two other options: '40MHz ch.36' and '40MHz ch.4'

Are connections on 2.4Ghz on the main host router good? 

>>> Yes, I can reach the internet when connected to directly to the main router.

>>> also these settings exist:

Wireless Access Point

✔ Enable Wireless Access Point

✔ Enable WPS

✔ Allow Broadcast of Name (SSID)

    Synchronise 2.4GHz and 5GHz Settings

>>> i.e. 2.4/5 are not 'synchronised' - if that makes a difference?

Thanks for your help